Mutable vs Immutable Infrastructure in DevOps

Let us talk a bit about Mutable and Immutable Infrastructure. And how does DevOps uses them to create a core for any environment.

In recent times, immutable infrastructure is becoming more popular and it is a huge shift. Traditionally, all infrastructure has been mutable. But as they say, change is the only constant. The same way it applies to the technologies used in business.

Nowadays majority of organizations tend to implement DevOps as a practice. So later in this article, we will also discuss why to use Immutable Infrastructure in DevOps.

What is Mutable Infrastructure?

Mutable simply means ‘changeable’ or ‘customizable’. Mutable means something that can be changed if and when needed. It allow you to do necessary changes and updates on a regular basis. It is possible to login into the server and update configurations and other details in case of a Mutable Infrastructure.

But there won’t be consistency in mutable infrastructure. Why?

Because each server might have different configurations and settings. It is hard to maintain the balance in configurations between various servers while using the Mutable Infrastructure.

Benefits of Mutable Infrastructure:

1. This infrastructure is a total customizable infrastructure. So it can accurately fit the needs of all the applications running on any server.
2. No need to establish a whole new server to fix some problems. IT staff will be aware of every server. Thus it is easier to find the problem.
3. It is possible to adapt the updates faster in each server separately.

But there are some limitations also of Mutable Infrastructure.

1. Technical issues are hard to find or reproduce in mutable infrastructure.
2. As each server has a different configuration, often called ‘configuration drift’.
3. Changes done to the server are not usually documented. Thus it makes more difficult to do version tracking.
4. You need to do manual configuration in each server which makes it a time consuming process.

Now what is actually an Immutable Infrastructure?

Immutable is the opposite of Mutable. Thus, it’s functionality is completely different from the Mutable Infrastructure. Immutable Infrastructure is something that cannot be changed or modified once established. The purpose behind this infrastructure is to build the components to match particular specifications. There is no room for modifications in the future.

If there are some changes that need to be done in the server, then a whole new infrastructure will be installed based on the updated requirements. Here, the previous infrastructure will be out of service as it is obsolete.

Benefits of Immutable Infrastructure:

1. Provides compatible environment to the servers.
2. QA/Testing is much more consistent from development to test to production.
3. There is no room for configuration drift. As long as the server is running, the IT staff knows the accurate state of that server. This will avoid any unexpected shocks.
4. It is simple to resolve the issue here. You only need to delete the instance which is causing the error. It also leds to less support calls.
5. It improves security incident resolution.
6. Immutable infrastructure takes the best advantage of the cloud. That is why a legitimate DevOps runs on immutable infrastructure.

Examples of Tools for Immutable Infrastructure:

Some of the  popular Immutable Infrastructure Tools are listed below. These tools can be leveraged to build great immutable infrastructure.

1. Terraform
2. Docker
3. Spinnaker
4. Kubernetes

Why DevOps uses Immutable Infrastructure?

Immutable infrastructure is used most by the DevOps. It is affordable and easy to create new servers using modern DevOps. If there is any room for updates or improvements in immutable infrastructure, you need to replace the whole server.

Immutable infrastructure is strongly correlated with the concept of infrastructure as a code. Infrastructure as a code allows you to to do all the planning of the components like instances, networking, and security. And then you can push in into your dev environment. As you promote those to dev environment and test and prod, it is quite easy to repeat these steps in a consistent manner with immutable infrastructure. This will also make sure that no matter what environment the app developers might be in, there will always be a consistent environment. They don’t need to worry about it while deploying applications.

For all these reasons, immutable infrastructure is highly associated with the DevOps practice. DevOps includes culture and tools that works to achieve agile development with continuous delivery. And continues delivery drives immutable infrastructure.